Continuous process for making electric blankets and pads with ptc wire

Abstract

A heating blanket, pad or pillow is produced from a continuous roll of substrate material over which a continuous length of resistance heating wire is arranged. Predetermined lengths of the resulting substrate and heating element are cut from the roll to produce individual heating products. PTC wire is preferably used for the resistance wire and facilitates a continuous manufacturing process.

What is claimed is:  
     
         1 . An electric heating assembly, comprising: 
 a pliable substrate; and    a resistance heating element arranged on said substrate, said resistance heating element having a first end portion receiving electrical power and a second free end portion spaced apart from said first end portion.    
     
     
         2 . The assembly of  claim 1 , further comprising a first electrical connector connected to said first end portion and a second electrical connector connected to said second end portion.  
     
     
         3 . The assembly of  claim 1 , wherein said resistance heating element is arranged in a serpentine pattern and wherein said substrate comprises a non-woven material.  
     
     
         4 . The assembly of  claim 1 , wherein said substrate comprises a fabric blanket shell.  
     
     
         5 . The assembly of  claim 1 , further comprising a blanket shell and wherein said substrate is disposed within said blanket shell.  
     
     
         6 . The assembly of  claim 1 , further comprising a safety circuit located externally of and spaced apart from said substrate and adapted to control electrical current to said resistance heating element.  
     
     
         7 . The assembly of  claim 1 , wherein said substrate comprises first and second spaced apart opposite end portions, wherein said resistance heating element extends longitudinally over said substrate, and wherein said first end portion of said resistance heating element is located adjacent said first end portion of said substrate and said second free end portion is located adjacent said second opposite end portion of said substrate.  
     
     
         8 . A method of manufacturing a heating assembly, comprising: 
 longitudinally moving a continuous sheet of pliable substrate material along a path;    applying a length of resistance heating wire to said moving sheet of substrate material;    severing predetermined lengths of said substrate material from said sheet of substrate material; and    severing said resistance wire adjacent opposite longitudinal end portions of said predetermined lengths.    
     
     
         9 . The method of  claim 8 , further comprising electrically connecting a safety circuit module to one end of said resistance heating wire at a location spaced apart from said severed predetermined lengths of said substrate.  
     
     
         10 . The method of  claim 9 , further comprising placing a connector on the opposite end of said resistance heating wire.